<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Ducks</title>
  <script>
function Duck(sound) { 
	this.sound = sound;
	this.quack = function() {
		console.log(this.sound);
	};
}
var toy = new Duck("quack quack"); 
toy.quack();
console.log(typeof toy); 
console.log(toy instanceof Duck);
  </script>
</head>
<body>
</body>
</html>
